linux-kernel - Re: [RFC][PATCH 6/6] objtool,x86: Rewrite retpoline thunk calls

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Date:   Sun, 21 Feb 2021 06:45:54 +0100
From:   Jürgen Groß <jgross@...e.com>
To:     Peter Zijlstra <peterz@...radead.org>,
        Borislav Petkov <bp@...en8.de>
Cc:     Josh Poimboeuf <jpoimboe@...hat.com>, x86@...nel.org,
        pjt@...gle.com, mbenes@...e.cz, linux-kernel@...r.kernel.org
Subject: Re: [RFC][PATCH 6/6] objtool,x86: Rewrite retpoline thunk calls

On 20.02.21 23:32, Peter Zijlstra wrote:
> On Sat, Feb 20, 2021 at 06:41:01PM +0100, Borislav Petkov wrote:
>>>   - if we had negative alternatives objtool doesn't need to actually
>>>     rewrite code in this case. It could simply emit alternative entries
>>>     and call it a day.
>>
>> I don't mind the negative alt per se - I mind the implementation I saw.
>> I'm sure we can come up with something nicer, like, for example, struct
>> alt_instr.flags to denote that this feature is a NOT feature.
> 
> So you don't like the ~ or - on cpuid? ISTR we talked about
> alt_instr::flags before, but Google isn't playing ball today so I can't
> seem to find it.

If you want I can cook up a patch and include it in my paravirt
cleanup series.

Juergen

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